Campbell's previous association with Torres came to an abrupt end after Andre Villas-Boas was sacked by trigger-happy Chelsea chairman Roman Abramovich.

"I only did about two or three sessions with Fernando but I could see his confidence coming back," Campbell said.

"The biggest problem is that when you lose your speed you're unable to do what you used to be able to do. So then you start trying harder and harder. But that can be counterproductive.

"If you want to be quick, there's an element of relaxation that's involved. You've only got to look at Gareth Bale. He runs at high speed but it's all relaxed and there's no tension in him.

"The problem with someone like Fernando Torres is that the harder he tries to find that speed, his efforts are actually detrimental."

Campbell traced Torres's problems to his injury-hit 2010 World Cup and highlighted two instances from the recent 0-0 draw with Manchester City to outline the extent of his troubles.

"Fernando got the ball and tried to knock it out of his feet and go past Vincent Kompany and James Milner, but they both caught him," said Campbell.

"Kompany we know is very quick but Milner is not exactly lightning by any stretch of the imagination.

"A striker without any natural speed wouldn't have knocked the ball out of his legs to chase after. It shows he is playing as if he still believes he has the speed but he clearly hasn't.

"A sprint coach could help him," he added. "I'm 100 per cent sure of that. I believe that if you can put the speed back into his legs then, boy, you will see a very different and far more confident Fernando Torres."